Winch with constant tension cable

ABSTRACT

A winch comprising a rotatable reel on which the cable can be wound and unwound, a rotatable guide pulley on which the cable passes from the reel to a load, a drive shaft driven at a substantially constant speed, and an eddy current electro brake coupling the reel and drive shaft to transmit a substantially constant torque therebetween while permitting relative limited angular rotation. A second eddy current electro brake is connected between the guide pulley and a stationary support.

United States Patent David et a1.

WINCH WITH CONSTANT TENSION CABLE Inventors: Pierre Y. David; .1061 M.Charles, both of La Valette; Robert Julien Antoine Toscano, La Seyne,Mer, all

of France Assignee: Etat Francais, Paris, France Filed: Dec. 10, 1973Appl. No.: 423,528

Foreign Application Priority Data Dec. 11, 1972 France 72.43940 1 June17, 1975 2,346,917 4/1944 Heger 242/45 2,411,094 11/1946 Johnson 254/1722,443,763 6/1948 Dahlgren et a1. 1. 254/172 2,575,476 1 1/1951 Traitt242/45 2,810,980 10/1957 Puretic t 1 1. 254/138 2,978,195 4/1961 Weberet a1. 1 1 242/45 3,049,308 8/1962 Lang 1 1 242/45 3,281,087 10/1966Claiborne et a1. 242/45 3,778,003 12/1973 Godderidgc 1. 242/45 PrimaryExaminer-Robert J. Spar Assistant Examiner-Kenneth Noland Attorney,Agent, or Firm-Waters, Schwartz & Nisscn [57] ABSTRACT A winchcomprising a rotatable reel on which the cable can be wound and unwound,a rotatable guide pulley on which the cable passes from the reel to aload, a drive shaft driven at a substantially constant speed, and aneddy current electro brake coupling the reel and drive shaft to transmita substantially constant torque therebetween while permitting relativelimited angular rotation. A second eddy current electro brake isconnected between the guide pulley and a stationary [56] ReferencesCited UNITED STATES PATENTS Support- 2,306,045 12/1942 Delano 242/155 MC3 Claims, 3 Drawing Figures u /4 T 6 3a 4 a i 5 B 21 1 WINCH WITHCONSTANT TENSION CABLE FIELD OF THE INVENTION The present inventionrelates to a constant tension winch driven by a constant speed drivemeans and associated methods.

The wind. of the invention is adapted for use in hauling or hoistingapparatus.

BACKGROUND A specific but non-limiting embodiment of a winch accordingto the invention is one for hauling or lifting a floating load by meansof a cable wound on said winch which is placed on a ship, a river bankor a pontoon. In such case, the floating load follows the swelling andsurging movements of the water and thus undergoes relative movement withrespect to the winch which is fixed or only follows the swelling andsurging movements of the water to a much reduced degree.

PRIOR ART The hauling or hoisting of a floating load is a problem whichis difficult to solve and currently a number of complex arrangementshave been proposed for interpositioning between the winch and the loadto compensate for the relative movements therebetween and to eliminateany substantial tension in the connecting cable which could causerupture thereof.

SUMMARY OF THE INVENTION An object of the invention is to provide awinch which avoids production of large forces in the cable and maintainsthe cable at substantially constant tension without utilizing anyintermediary equipment between the winch and the load, but while using adrive of constant speed.

The winch according to the invention is of the type comprising a reeland a guide pulley for the cable.

The reel is driven via an eddy current electro brake whose rotor is fedby a constant intensity current, the rotor being secured to said reeland the stator to a motor shaft driven at constant speed. The guidepulley is secured to the stator of a second eddy current brake motorwhose rotor is fixed to the casing of the winch and fed by a constantintensity current.

Eddy current electro brakes are well known and composed of a rotor witha coil adapted to produce a magnetic field and a stator in which eddycurrents are developed which absorb energy and produce a brakage of therotor.

The invention is directed to an apn ication of such electro brakes ascoupling members. W hen the rotor of the electro brake is fed with acurrent of constant intensity, the torque which is transmitted remainsconstant over a range of relative speed between the stator and rotor,for example between 2000 and 4000 rpm.

If the drive shaft rotates at a constant speed of 3000 rpm, the winchcan rotate at speeds of about 1000 rpm greater and lower than this speedi.e. between 2000 and 4000 rpm without substantial variation of thetorque and hence with constant tension in the cable.

The cable therefore can be wound or unwound according to the movementsof the load while remaining constantly taut and subjected to a constanttension.

With a reel of conventional diameter, the speed variation correspondingto winding and unwinding of the cable will be between i 6 meters persecond which encompasses prevailing increasing or decreasing speeds dueto swell or surge.

The guide pulley of the cable is disposed at the discharge end of thereel and is braked by an electro S brake, said guide pulley beingeffective to the operation to assure constant tension in the cable whilepreventing slack between the reel and the pulley.

The characteristic features of the invention will next become apparentfrom the following description of an embodiment thereof given by way ofexample and not of limitation with reference to the attached drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a longitudinal sectional viewof an embodiment of the invention;

FIG. 2 is a plan view thereof; and

FIG. 3 is a transverse sectional view thereof.

DETAILED DESCRIPTION In the drawing, the reference character 1represents a chassis for a winch formed of a base composed of channelmembers. At the two extremities of the chassis there are mounted flanges2a and 2!) serving as bearing supports and having respective bores 3a,3b in which are lodged roller bearings 4 and 5 respectively. The bearing4 supports a drive shaft II and the bearing 5 supports a shaft 13 of areel 14 of a winch.

The flange 2b is provided with a second bore in which a roller bearing 7is mounted which supports one end of a threaded shaft 8, the other endof shaft 8 being supported in a roller bearing 10 mounted in a flange 9secured to chassis l. The shaft 8 carries a cable distributor 22.

Numeral 6 designates a drive pulley on the drive shaft 11.

Numeral represents an eddy current electro brake which serves as asynchronous electromagnetic coupler between drive shaft 1] and reel 14.This type of electro brake is well known in the art and will not bedescribed in detail.

The stator of the coupler is keyed on the drive shaft 11. The rotor issecured to the reel 14 by the screws I2. FIG. 1 shows the collector 17of the rotor and the electrical feed terminals 18.

A toothed wheel 19 is fixed between the reel 14 and the collector 17.The wheel 19 is in mesh with a pinion 20 keyed on shaft 8.

The cable distributor 22 is constituted by a nut 23 mounted on thethreaded portion of shaft 8 and carrying a pulley 24 provided with agroove in which the cable 16 passes. The nut 23 has an integral stubshaft 28 which is slidably mounted in guides 34 to prevent turning ofthe nut. When the reel rotates, it entrains the shaft 8 in rotation andthe nut 23 travels axially along the shaft. The pulley 24 thereforecauses the cable 16 to be wound onto or unwound from the reel in regularfashion.

FIG. 3 shows a guide pulley 51 for the cable I6. The cable 16 passes inthe groove of pulley 51 and it is maintained thereat by a pulley 44under the bias of spring 39 acting on pulley 44.

Pulley 51 serves as a brake for cable winding. Pulley S1 is mounted on ashaft 40. An eddy current electro brake 54 of the same type as thatdiscussed above is utilized and the stator of the brake 54 is keyed onshaft 40 while the rotor 48 is fixed to a plate 55 secured to thechassis.

According to a non-limiting example. the cable 16 has a diameter of 4mm. It is wound for only one single turn on the reel whose exteriordiameter is [60 mm. The length of the cable is about 30 meters.

The recall force exerted by the cable 6 is about 500 Newtons. The pulley6 is driven at a speed of 3000 rpm.

When the electro brake I5 is fed with constant current, the torqueexerted on the reel remains substantially constant even though therelative speed between the rotor and the stator of the coupler can varyby l000 rpm in either direction, i.e. be in the range between 2000 and4000 rpm.

Such a winch therefore maintains a constant tension in the cable even ifthe winch and the load connected to the cable are subject to a relativemovement as long as the speed of winding of the winch is between i 1000rpm of that of the drive shaft which speeds corresponds to a variationof speed of winding of the cable between t 6 meters/second, the cabletherefore being able to unwind or wind up to follow the movements of theload and avoid high stress while the pulley 6 continues to turn alwaysin the same direction and at the same speed. This range of speed of i 6meters/second incorporates the current speeds which are met in the caseof a craft which follows the movement of swelling and surging of thewater.

A specific application of the winch conforming to the invention is ahauling winch for a floating load to bring the load under a liftinggrapple which is the subject of separate application Ser. Nos. 278.798and 797 filed Aug. 8, 1972. In this case, the relative movement of thehoisting apparatus and the floating load due to sea swell are absorbedby the winding and unwinding of the cable without modification of theforce of the hoisting apparatus.

When the electrical energization of the coupler is terminated, a simplemanual traction on the cable is stiff:- cicnt to unwind the same.

Other utilizations for such winches of constant tension can be found forall cases of hoisting or hauling by means of a cable of a load subjectto oscillation movement with respect to the winch.

It is well understood that numerous modifications of the disclosedembodiment will become obvious to those skilled in the art withoutdeparting from the scope and spirit of the invention as defined in theappended claims.

What is claimed is:

l. A constant tension winch for drawing a cable with a load comprising,in combination:

a rotatable reel on which a cable can be wound or unwound, the tensionof said cable being kept sub stantially constant;

constant speed drive means comprising a drive shaft with continuousconstant rotation in the same direction independent of whether the cableis wound or unwound;

an eddy current electrobrake including a spooled rotor secured to saidreel and a stator secured to said drive shaft, the rotor being suppliedwith current; and

means for keeping the intensity of said current constant,

a substantially constant torque being transmitted between said drivemeans and said reel over a predetermined range of relative speed betweensaid stator and rotor.

2. A constant tension winch as claimed in claim 1 wherein said range ofrelative speed is between 2000 and 4000 rpm.

3. A constant tension winch for hauling or hoisting a cable with afloating load comprising, in combination,

a rotatable reel on which a cable can be wound or un wound, the tensionof said cable being kept substantially constant,

constant speed drive means comprising a drive shaft with continuousconstant rotation in the same direction independent of whether the cableis wound or unwound;

an eddy current electrobrake including a spooled rotor secured to saidreel and a stator secured to said drive shaft, the rotor being suppliedwith current; and

means for keeping the intensity of said current constant,

a substantially constant torque being transmitted between said drivemeans and said reel over a predetermined range of relative speed betweensaid stator and rotor.

1. A constant tension winch for drawing a cable with a load comprising,in combination: a rotatable reel on which a cable can be wound orunwound, the tension of said cable being kept substantially constant;constant speed drive means comprising a drive shaft with continuousconstant rotation in the same direction independent of whether the cableis wound or unwound; an eddy current electrobrake including a spooledrotor secured to said reel and a stator secured to said drive shaft, therotor being supplied with current; and means for keeping the intensityof said current constant, a substantially constant torque beingtransmitted between said drive means and said reel over a predeterminedrange of relative speed between said stator and rotor.
 2. A constanttension winch as claimed in claim 1 wherein said range of relative speedis between 2000 and 4000 rpm.
 3. A constant tension winch for hauling orhoisting a cable with a floating load comprising, in combination, arotatable reel on which a cable can be wound or unwound, the tension ofsaid cable being kept substantially constant, constant speed drive meanscomprising a drive shaft with continuous constant rotation in the samedirection independent of whether the cable is wound or unwound; an eddycurrent electrobrake including a spooled rotor secured to said reel anda stator secured to said drive shaft, the rotor being supplied withcurrent; and means for keeping the intensity of said current constant, asubstantially constant torque being transmitted between said drive meansand said reel over a predetermined range of relative speed between saidstator and rotor.